package com.ppdai.infrastructure.mq.biz.common.trace;

import java.util.Iterator;
import java.util.ServiceLoader;

public class ServiceBootstrap {
	public static <S> S loadFirst(Class<S> clazz) {
		Iterator<S> iterator = loadAll(clazz);
		if (!iterator.hasNext()) {
			throw new IllegalStateException(String.format(
					"No implementation defined in /META-INF/services/%s, please check whether the file exists and has the right implementation class!",
					clazz.getName()));
		}
		return iterator.next();
	}

	private static <S> Iterator<S> loadAll(Class<S> clazz) {
		ServiceLoader<S> loader = ServiceLoader.load(clazz);

		return loader.iterator();
	}
}
